Light emitting device and method of fabricating the same

Abstract

A light-emitting device according to an exemplary embodiment of the present invention includes a first conductivity-type semiconductor layer disposed on a substrate; an active layer disposed on the first conductivity-type semiconductor layer; a second conductivity-type semiconductor layer disposed on the active layer; and an irregular convex-concave pattern disposed on a surface of the first conductivity-type semiconductor layer. The irregular convex-concave pattern includes convex portions and concave portions, and the convex portions have irregular heights and the concave portions have irregular depths. The first conductivity-type semiconductor layer including the irregular convex-concave pattern is exposed from the active layer and the second conductivity-type semiconductor layer.

What is claimed is: 
     
       1. A light-emitting device, comprising:
 a first conductivity-type semiconductor layer disposed on a substrate; 
 an active layer disposed on the first conductivity-type semiconductor layer; 
 a second conductivity-type semiconductor layer disposed on the active layer; 
 an irregular convex-concave pattern disposed on a surface of the first conductivity-type semiconductor layer; and 
 a first electrode pad, 
 wherein the irregular convex-concave pattern comprises convex portions and concave portions, the convex portions comprising irregular heights, the concave portions comprising irregular depths, 
 wherein the first conductivity-type semiconductor layer comprising the irregular convex-concave pattern is exposed from the active layer and the second conductivity-type semiconductor layer, 
 wherein the irregular convex-concave pattern is disposed between the first electrode pad and the second conductivity-type semiconductor layer, 
 wherein the first conductivity-type semiconductor layer comprises first, second, and third N-GaN layers, the first and third N-GaN layers being doped with a higher density of n-type impurities than the second N-GaN layer, and 
 wherein a first part of the concave portions of the irregular convex-concave pattern extend to a portion of the second N-GaN layer or over an entire region of the second N-GaN layer, or extend to an upper region of the first N-GaN layer. 
 
     
     
       2. The light-emitting device of  claim 1 , wherein the third N-GaN layer is in ohmic contact with the first electrode pad, and the irregular convex-concave pattern is disposed on the third N-GaN layer. 
     
     
       3. The light-emitting device of  claim 1 , wherein the irregular convex-concave pattern is disposed below the active layer. 
     
     
       4. The light-emitting device of  claim 1 , further comprising:
 a first electrode pad disposed on the exposed surface of the first conductivity-type semiconductor layer; and 
 first electrode legs extending from the first electrode pad, 
 wherein the irregular convex-concave pattern is disposed under the first electrode pad and under the first electrode legs. 
 
     
     
       5. The light-emitting device of  claim 1 , further comprising:
 a first electrode pad disposed on the exposed surface of the first conductivity-type semiconductor layer, 
 wherein an upper portion of the first conductivity-type semiconductor layer contacting the first electrode pad comprises a flat surface. 
 
     
     
       6. The light-emitting device of  claim 5 , wherein each of the convex portions of the irregular convex-concave pattern comprises a first end disposed coplanar with the flat surface or below the flat surface. 
     
     
       7. The light-emitting device of  claim 5 , wherein each of the convex portions of the irregular convex-concave pattern comprises a first end disposed coplanar with the flat surface or above the flat surface. 
     
     
       8. The light-emitting device of  claim 5 , further comprising:
 a second electrode pad disposed on the second conductivity-type semiconductor layer; and 
 a transparent conductive layer disposed between the second conductivity-type semiconductor layer and the second electrode pad, 
 wherein a lateral distance between the first electrode pad and the transparent conductive layer is in a range from 5 μm to 50 μm. 
 
     
     
       9. The light-emitting device of  claim 5 , further comprising:
 first electrode legs extending from the first electrode pad; 
 a second electrode pad disposed on the second conductivity-type semiconductor layer; and 
 second electrode legs extending from the second electrode pad and alternating with the first electrode legs to be disposed parallel to the first electrode legs, 
 wherein the irregular convex-concave pattern comprises a first irregular convex-concave pattern overlapping the first electrode legs to be disposed parallel thereto, a second irregular convex-concave pattern extending from the first irregular convex-concave pattern towards the second electrode legs, and a third irregular convex-concave pattern disposed in an edge region of the light-emitting device. 
 
     
     
       10. The light-emitting device according to  claim 5 , further comprising:
 a second electrode pad disposed on the second conductivity-type semiconductor layer, the first and second electrode pads comprising a dome structure. 
 
     
     
       11. The light-emitting device of  claim 1 , wherein the first conductivity-type semiconductor layer is exposed along an edge region of the light-emitting device, and the irregular convex-concave pattern is disposed on the exposed surface of the first conductivity-type semiconductor layer along the edge region. 
     
     
       12. The light-emitting device of  claim 11 , wherein the edge region comprises a corner region and a lateral region, the corner region comprising a greater width than the lateral region. 
     
     
       13. The light-emitting device of  claim 1 , wherein the irregular convex-concave pattern in the first conductivity-type semiconductor layer comprises a height lower than that of the first conductivity-type semiconductor layer under the irregular convex-concave pattern. 
     
     
       14. The light-emitting device of  claim 1 , wherein the irregular convex-concave pattern comprises a height in a range from 160 nm to 3 μm.